1. Field of the Invention
The invention relates to thickening solid suspensions and more particularly refers to a new and improved method and apparatus for dewatering solid suspensions of varying concentration down to a low residual moisture by means of pusher centrifuge which has disposed ahead of it at least one hydrocyclone or at least one group of hydrocyclones.
2. Description of the Prior Art
Hydrocyclones and pusher centrifuges are known for use in dewatering. In dewatering solid suspensions by means of an arrangement consisting of hydrocyclones and a pusher centrifuge, problems arise if a low residual moisture is to be obtained under conditions in which the concentration of the suspension varies. If the conditions are set to produce a solid with a certain residual moisture not in excess of, say 3% (i.e., three percent by weight are crystal surface water), an increased concentration of solids in the fed-in suspension leads to disturbances of the operation. Increased solid concentration of the fed-in suspension may cause the lower outlet of a hydrocyclone to get clogged up. There is also the danger that the liquid leaving the upper outlet of the last hydrocyclone is still loaded with solids, i.e. is insufficiently purified. Also difficulties arise in consistently obtaining a uniform product with low water content.